USB Chip/Smart Card Interface Device (CCID) specification is a standard established by some world-leading IT enterprises, and provides a possibility of communicating between the smartcard reader/writer and the host (including the embedded host). The CCID communicates with the host via the USB interface, and communicates with the smartcard in accordance with the ISO 7816 standard. The CCID driver is provided and supported by Microsoft Windows 2000 or higher. Thus, manufacturers are able to develop devices complying with the CCID interface standard easily. In addition, the CCID standard supports a PC/SC (Personal Computer/Smart Card) interface calling. A number of open source CCID drivers are also available for other open source operating systems, such as the various versions of Linux.
The CCID protocol is a single-channel protocol and supports access to multiple card slots. But only one card slot can be accessed when an operation is performed on the card reader with the CCID driver provided by Microsoft.